Refrigeration, insulation, ice, and dry ice have conventionally been used to ship temperature-sensitive products, such as pharmaceuticals and biological samples. U.S. Pat. No. 3,480,015 describes an electrically operated refrigeration unit employing a chilling convective air flow to draw heat from blood collection bags deposited within an insulated compartment. U.S. Pat. No. 2,467,268 describes a method for shipping chilled elements by alternately interleaving them with dry ice packs; thermal insulating means are disposed intermediate the item to be chilled and the dry ice to prevent heat transfer by conduction and resulting overchilling. U.S. Pat. No. 4,276,752 describes a refrigerated cargo container for use in transporting temperature sensitive cargoes in aircraft.